<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>

</head>
<body>
    <div id="app">
        <div v-if="awesome">
            <label for="">用户名</label>
            <input type="text" placeholder="用户名登录" key="user-key">
        </div>
        <div v-else>
            <label for="">邮箱</label>
            <input type="text" placeholder="邮箱登录" key="email-key">
        </div>

        <button @click="awesome=!awesome">切换按钮</button>
    </div>    

    <script>
        var app = new Vue({
            el:"#app",
            data:{
                awesome:true,
              
            },
           
        });
    </script>
</body>
</html>
